GB425739A - Improvements in or relating to thermionic valve arrangements - Google Patents

Abstract

425,739. Thermionic valves. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE, 12, Hallesches Ufer, Berlin. July 5, 1934, No. 19820. Convention date, July 5, 1933. [Class 39 (i)] In valves having indirectly-heated cathodes the cathode heater and leads therefor are screened by means within the valve envelop and means external thereto, these two means being either electrostatically coupled or connected to each other. In one form the cathode body 5, Fig. 1, which holds the emissive material is carried down and has an extension 9 to form a complete internal screen for the heater and leads 3 ; capacitatively coupled with the extension 9 is an external screen 10, which may enclose a heater supply-transformer 11 and is connected to the screened cable 12. In a modification wherein heater supply plugs in the valve base enter a holder, a metal screening tube may surround the leads from the valve pinch to the plugs, and another tube may surround the holder sockets, the holder being itself covered with a screening layer. In valve constructions wherein the heater leads 3, Fig. 3, enter the valve through a pinch remote from the main leads, a screen 30 divides the valve into two parts and a coating 31 surrounds at least the heater side of the valve. In modifications a screening tube surrounds the pinch for the heater leads.